Three known methods of curing concrete products are first, using a steam ambient, second, using a carbon dioxide atmosphere, and third, using an autoclave process.
In the first method, a time period of several hours of steam curing plus 28 days of standard atmospheric conditions are required for hydration to be completed. The second method stimulates the curing process as to the amount of time involved, but the blocks take on a dark cast from the CO.sub.2 and still require 28 days of atmospheric curing. The third method, subjecting the products of steam at high pressures, does decrease the amount of curing time to a more satisfactory figure, but involves a considerable more expenditure of monies as compared to the other two methods. Furthermore, the quality of the product is questioned as to the autoclave method.